ENTEROBACTERIACEAE Flashcards
RAPID LACTOSE FERMENTERS
Escherichia coli
Klebsiella spp
Enterobacter spp.
NON-LACTOSE FERMENTERS
Salmonella spp except for S. arizonae
Shigella except S. sonnei
Proteus
Providencia
Morganella
Edwardsiella
LATE LACTOSE FERMENTERS
Salmonella arizonae
Shigella sonnei
Serratia spp
Hafnia spp
Yersinia spp
Citrobacter
Triple Sugar Iron (TSI) pH indicator
Phenol Red
TSI H2s indicator
Sodium thiosulfate is reduced to Sulfur Dioxide and Hydrogen Sulfide which reacts with Ferrous Sulfate
to produce black ferric sulfide
To determine if a g- bacilli
decarboxylates or
deaminates lysine and forms
H2S
Lysine Iron Agar (LIA)
If oxidative deamination of lysine
occurs
it will form a burgundy (red) color on
the slant in the presence of ferric ammonium
citrate and flavin mononucleotide.
If deamination does not occur
LIA slant remains purple
When glucose is fermented, the butt of
the medium becomes
acidic (yellow)
If the organism produces lysine
decarboxylase
cadaverine (purple) is
formed
If the decarboxylase is not produced,
the butt remains
acidic (yellow)
check organism (+) for
deamination
Slunt part
check organism (+) for
deamination
Slunt part
check organism (+) for
decarboxylation
Butt part
Organisms that involved deamination
Proteus, Morganella and Providencia
if the bacteria can produce sulfide
it will result of blackening
SULFIDE (H2S+)
INDOLE Result
Pink ring formation (+)
need Kovac’s reagent/Ehrlich’s reagent
POSITIVE IN INDOLE
Proteus vulgaris
NEGATIVE IN INDOLE
Proteus mirabilis
SIM would have heavy turbidity.
Can also form a brush like formation.
If the organism shows this it is
automatically
MOTILITY
To determine if the m/o is capable
of utilizing citrate as its sole source
of carbon.
CITRATE UTILIZATION TEST
POSITIVE REACTION FOR CITRATE
BLUE
NEGATIVE REACTION FOR CITRATE
GREEN CITRATE
Citrate useful in identification of lactose
fermenters
E, K, E
Positive organisms in Citrate Utilization Test
Klebsiella and
Enterobacter
Negative organisms in Citrate Utilization Test
Escherichia coli
To identify the rapid urease
producers and weak urease
producer
Urease Test
POSITIVE RESULT FOR UREASE
Pink/Red formation
NEGATIVE RESULT FOR UREASE
Yellow color
BROTH USE IN UREASE TEST
Christensen’s agar/
Stuart broth
Rapid Urease producers within 2-4 hrs
Proteus, Providencia and Morganella
Weak Urease producers more than 4 hrs
Kleibsiella pneumoniae and
Enterobacter spp, Yersinia spp, Serratia
and Citrobacter
Sugars in TSI
Lactose= 10
Sucrose=10
Glucose=1
pH indicator of MacConkey agar
neutral red
only media for detecting gram negative
in hospital settings
Selective for gram negative organisms
Carbohydrate present: Lactose
Differential media: it differentiate
lactose fermenters and non lactose
fermenter
MacConkey agar
If organism is lactose fermenters
pink
colonies
ENTEROBACTERIACEAE
GENERAL CHARACTERISTICS
Gram (-)
Facultative anaerobic
Glucose fermenters
Oxidase (-)
Motile with peritrichous flagella
(except
Klebsiella, Shigella, Yersinia
Non-encapsulated (except
Klebsiella
and Enterobacter)
Catalase (+) (except
Salmonella
dysenteriae)
Nitrate reducers (except
Erwinia and
Pantoea agglomerans)
Often with Gas production (except
Shigella, Salmonella, Proteus and
Providencia)
Commensal flora in the intestinal
tract (except
Salmonella, Shigella and Yersinia
Nonhemolytic except
In BAP: Escherichia coli- beta hemolysis
